Analysis And Research On Dynamic Characteristics Of Hydraulic System Of Working Face Support

For a long time,the liquid supply technology of fully mechanized coal mining face in China has been seriously lagging behind,especially in the aspects of liquid supply quality,efficiency,intelligent level and environmental friendliness,which can not meet the requirements of rapid development of safe and efficient intelligent mine,and has become a bottleneck restricting the development of fully mechanized coal mining intelligent technology.There are many actuators,complex actions and long liquid supply pipeline of hydraulic support in working face,which lead to the problems of slow response speed,low utilization efficiency and large loss along the way in long distance liquid supply system.Therefore,it is difficult to realize the pressure stabilization control and real-time control of emulsion pump station,resulting in the lag of liquid supply in working face,the difficulty of timely support and follow-up of hydraulic support,and affecting the rapid progress of coal mine working face.Therefore,this paper proposes to study the dynamic characteristics of the hydraulic system of the hydraulic support in the working face,and analyze the pressure flow characteristics of the hydraulic support in the full cycle time-sharing condition and the dynamic resistance characteristics of the liquid supply pipeline,which has important theoretical significance and engineering application for realizing the pressure prediction control,system pressure stabilization control of the hydraulic system of the hydraulic support and improving the liquid supply technology level of the fully mechanized working face Value.The main contents are as follows:(1)Theoretical analysis of hydraulic support hydraulic system.This paper expounds the composition and working principle of hydraulic system of support in fully mechanized working face of Guotun coal mine,mainly including column lifting control circuit and pushing jack sliding control circuit.Theoretical analysis of the hydraulic support in the process of lifting column and sliding frame,hydraulic support moving speed and sliding speed.(2)Dynamic and static characteristics analysis of long distance liquid supply pipeline.The pressure loss of the liquid supply pipeline is calculated theoretically,the theoretical model of the dynamic characteristics of the pipeline is established,and the pipeline system is simplified appropriately.The double inlet and single return liquid supply pipeline model is established.The dynamic characteristics of the pipeline and the pressure loss flow characteristics are simulated and analyzed,and the rationality of the pipeline model is verified by comparing with the theoretical analysis results.(3)Modeling and performance analysis of key valve parts of hydraulic support.The structure and working principle of electromagnetic unloading valve,safety valve and hydraulic control check valve are introduced.The corresponding simulation model is established.The characteristics of unloading recovery pressure of electromagnetic unloading valve,opening overflow closing characteristics of tower safety valve and pressure loss flow characteristics of hydraulic control check valve are simulated and analyzed.(4)Analysis and Research on dynamic characteristics of hydraulic support hydraulic system.The whole model of hydraulic system of working face support is established,and the characteristics of hydraulic support single frame moving,group pushing speed and displacement are analyzed;the initial support force of hydraulic support and the influencing factors of pressure in the lower cavity of column during the movement of the frame are analyzed;the pressure flow characteristics of one shift period of single hydraulic support in the working face,pressure flow characteristics at the outlet of pump station,and supply are analyzed The dynamic resistance characteristics and its influencing factors of the hydraulic pipeline system are analyzed.In this paper,the overall model of the hydraulic system of the working face support and the hydrodynamic model of the double inlet and single return liquid supply pipeline are established,and the modeling and performance analysis of the key valve components of the hydraulic support are completed.The simulation results show that:1)The results show that the pressure loss of the single inlet and single return liquid supply pipeline is too large,the double inlet and double return pipeline takes the second place,and the three inlet and three return pipeline is more ideal;the relative error of the pressure loss of the double inlet and single return liquid supply pipeline is 2.97% and 3.31%,respectively,which verifies the rationality of the liquid supply pipeline model.2)The key valve components of hydraulic support have good dynamic performance,which verifies the rationality of the key valve component model.3)The pressure flow curve and the dynamic resistance characteristic curve of the hydraulic support system were obtained.When the load of the executive end of the hydraulic support remains unchanged,the pressure loss of the liquid supply pipeline is stable at about 7 MPa.Due to the influence of the pressure loss of the liquid supply pipeline and various hydraulic valves,the initial support force of the column is less than 31.5Mpa,and the initial support force of the hydraulic support at the head end is only 19 mpa.With the increase of the distance between the hydraulic support and the end of the working face,the initial support force gradually decreases,and the difference between the initial support force of the hydraulic support at the head and end of the working face reaches 1.8MPa.4)The longer the pipeline is,the greater the pressure loss is,the lower the fluctuation frequency is,and the slower the dynamic response speed is.The larger the pipe diameter is,the smaller the pressure loss is and the more obvious the change is,and the smaller the fluctuation range is.Compared with the three inlet pipeline,the double inlet pipeline has larger pressure loss and obvious fluctuation.5)Through further simulation,the pressure flow curve of the hydraulic support inlet is obtained when the two hydraulic supports are inserted and moved.By moving the two hydraulic supports at the same time,the moving speed of the hydraulic support and the initial support force of the hydraulic support when lifting the column can be improved.However,when the moving action is switched,the pressure and flow fluctuation of the hydraulic support inlet is obvious,and the system is not stable.